Jack:A type of audio connector originally developed for telephone switchboards, and sometimes called a phone connector. Still in common use for musical and other audio equipment.
More info: Jack Connectors

Jump Cut:A video transition in which one shot appears to "jump" to another shot with very similar framing. Usually considered undesirable but can be used for dramatic effect.More info: Jump cuts

Jump the Shark:A colloquial term used mainly in the US, referring to a defining point in a TV or movie series that marks the beginning of a terminal decline in quality and/or popularity. It stems from the Happy Days episode in which the Fonz literally jumps a shark while waterskiing.More info: Jump cuts